Hydraulic expansion device



Aug. 25, 1953 JOHNSON 2,649,691

HYDRAULIC EXPANSION DEVICE i e es. 2, 1949 STATIONARY BASE A LONG PISTON IO l rDOG x PIVOT OF DOG STATIONARY LONG MOVING CYLINDER I 4o 24 q 4 D %/7A 32 Z5 zi o r INVENTOR.

Patented Aug. 25, 1953 UNITED STATES PATENT OFFICE 2,649,691 HYDRAULIC EXPANSION DEVICE Ervin G. Johnson, Oakland, Calif.

Application December 2, 1949, Serial No. 130,829

6 Claims.

1 The main objectof my invention is to translate low pressure into a high value of thrust without increasing the areas over which fluid pressure is exerted in like ratio. Other objects and advantages will be evident from the drawing which shows a section through my device.

The stationary piston I is received in a fluid pressure responsive member providing a traveling cylinder l2 having a long bore I 4. Cylinder I2 carries integral piston 16 on which is positioned another fluid pressure responsive member providing a floating cylinder 18 having integral therewith the small transmitting piston 20 which slides in the cylinder 22 which is integral with cylinder [2 through a piston portion 24. Piston 24 works in another fluid pressure responsive member providing thrust cylinder 26 which engages the work. Hydraulic fluid is trapped in chamber 28, a passage 40 being provided controlled by valve 38 which valve is closed during operation. The space 30 is vented as by passages 32 and 34 as shown.

The entire assembly including elements l2 to 34 moves under pressure from a pump acting through passage H extending through piston I0 into the cylinder [2 and into the chamber formed by the first and the third mentioned pressure responsive members until cylinder 26 engages the reaction member forming the Work to be thrust upon. Dogs 36 forming another reaction member now move into the position shown to make the cylinder [2 rigidly stationary. Additional fluid pumped into the chamber I exerts thrust on the floating piston [8 equal to pressure P1 multiplied by the area A1 of said piston I 8. Where A2 equals the area of piston and A3 equals the area of piston 26, the gross thrust on the work pieceis Pw equals A3 A1 P1 divided by the area of piston 20. The smaller A2 is, the greater is the Pw.

I claim:

1. A movable fluid pressure multiplying expansion unit for the purpose of expansively engaging juxtaposed areas of engagement of opposed spaced apart reaction members to cause them to experience expansive forces tending to separate them comprising, in combination: two fluid pressure responsive members providing a first variable volume pressure chamber there-between and providing a pair of opposed complementary pressure areas partially defining walls for such chamber and each member further providing an exposed surface of engagement for directly engaging the juxtaposed areas of such reaction members; a third fluid pressure responsive member, said third pressure responsive member and one of said first mentioned two pressure responsive members together providing a second variable volume pressure chamber therebetween and providing opposed complementary pressure areas partially defining walls for said second chamber; and means for transmitting the entire thrust of the third member into the first chamber.

2. A device as in claim 1, and means for applying energy within the second chamber to cause expansion thereof.

3. A device as in claim 1, and means for applying energy within the second chamber to cause expansion thereof comprising means providing a fluid conductor having provision for allowing movement of the unit with respect to the reaction members.

4. A device as in claim 1, means for applying energy within the second chamber to cause expansion thereof, and means for supporting the unit for movement with respect to the reaction members.

5. A device as in claim 1, supporting means for said unit and means for moving said unit with respect to the supporting means, and means for transmitting energy to said first chamber to cause expansion thereof.

6. A device according to claim 1, said last named means being a single rigid member.

ERVIN G. JOHNSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 556,196 Molas Mar. 10, 1896 584,712 Shem June 15, 1897 841,972 Huber Jan. 22, 1907 1,888,990 Kurath Nov. 29, 1932 1,911,918 Miller et al May 30, 1933 2,058,377 Francis Oct. 20, 1936 2,351,872 Parker June 20, 1944 

